[Sync] Make syncer commands avoid posting tasks on threads with no work to do

chrome/browser/sync/engine/model_changing_syncer_command_unittest.cc

+// Copyright (c) 2011 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/basictypes.h"
+#include "base/memory/ref_counted.h"
+#include "chrome/browser/sync/engine/model_changing_syncer_command.h"
+#include "chrome/browser/sync/sessions/sync_session.h"
+#include "chrome/browser/sync/syncable/model_type.h"
+#include "chrome/browser/sync/test/engine/fake_model_worker.h"
+#include "chrome/browser/sync/test/engine/syncer_command_test.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace browser_sync {
+
+namespace {
+
+class FakeModelChangingSyncerCommand : public ModelChangingSyncerCommand {
+ public:
+  FakeModelChangingSyncerCommand() {}
+  virtual ~FakeModelChangingSyncerCommand() {}
+
+  const std::set<ModelSafeGroup>& changed_groups() const {
+    return changed_groups_;
+  }
+
+ protected:
+  virtual std::set<ModelSafeGroup> GetGroupsToChange(
+      const sessions::SyncSession& session) const {
+    return session.GetEnabledGroups();
+  }
+
+  virtual void ModelChangingExecuteImpl(sessions::SyncSession* session) {
+    changed_groups_.insert(session->status_controller().group_restriction());
+  }
+
+ private:
+  std::set<ModelSafeGroup> changed_groups_;
+
+  DISALLOW_COPY_AND_ASSIGN(FakeModelChangingSyncerCommand);
+};
+
+class ModelChangingSyncerCommandTest : public SyncerCommandTest {
+ protected:
+  ModelChangingSyncerCommandTest() {}
+  virtual ~ModelChangingSyncerCommandTest() {}
+
+  virtual void SetUp() {
+    workers()->push_back(
+        make_scoped_refptr(new FakeModelWorker(GROUP_UI)));
+    workers()->push_back(
+        make_scoped_refptr(new FakeModelWorker(GROUP_PASSWORD)));
+    (*mutable_routing_info())[syncable::BOOKMARKS] = GROUP_UI;
+    (*mutable_routing_info())[syncable::PASSWORDS] = GROUP_PASSWORD;
+    SyncerCommandTest::SetUp();
+  }
+
+  FakeModelChangingSyncerCommand command_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ModelChangingSyncerCommandTest);
+};
+
+TEST_F(ModelChangingSyncerCommandTest, Basic) {
+  ExpectGroupsToChange(command_, GROUP_UI, GROUP_PASSWORD, GROUP_PASSIVE);
+  EXPECT_TRUE(command_.changed_groups().empty());
+  command_.ExecuteImpl(session());
+  EXPECT_EQ(command_.GetGroupsToChangeForTest(*session()),
+            command_.changed_groups());
+}
+
+}  // namespace
+
+}  // namespace browser_sync